A mobile body such as a vehicle having a battery mounted therein uses energy supplied from the battery for driving the vehicle or for other purposes. The energy output efficiency or other factors of the battery are affected by temperature. In particular, at low temperatures, because the viscosity of a liquid electrolyte within the battery or reaction resistance is increased, sufficient power cannot be obtained, and, on the other hand, if the temperature is too high, battery constituent materials may be adversely affected. Therefore, management of the temperature of the battery is important.
Patent Document 1 describes a structure provided with a heat exchanger for circulating a heating medium to be circulated in a water-cooled engine, in which this heat exchanger is used to warm up a battery. Further, Patent Document 2 discloses that a battery is heated by heat (Joule heat) generated in electric wire for driving a motor using power supplied from a generator.